<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>

<script>
    document.write("Math.abs(-123)=" + Math.abs(-123) + "<br>")
    document.write("Math.abs(123)=" + Math.abs(-123) + "<br>")
    document.write("Math.PI=" + Math.PI + "<br>")
    document.write("Math.ceil(3.4)=" + Math.ceil(3.4) + "<br>")
    document.write("Math.floor(3.4)=" + Math.floor(3.4) + "<br>")
    // 生成0-1之间的随机数
    document.write("Math.random()=" + Math.random() + "<br>")

</script>
</html>